Hi Steve
Deletion is not archiving.
If you followed the standard archiving process, as described on the link below, then you can access the BOM. The process to access the archived BOM is described also on the link.
Archiving PP-BOMs (PP-BD-BOM) - Production Planning and Control (PP) - SAP Library
If you have simply deleted the BOM on transaction CS02, then it is not accessible on any transaction. The records are also deleted from the table and you cannot access them anymore.
BR
Caetano